Field of the Invention
The present invention relates to an imprint apparatus, an imprint method, and an article manufacturing method.
Description of the Related Art
The demand for micronization of semiconductor devices, magnetic recording media, and MEMS and the like is increasing, and in addition to the conventional photolithography technology, a microfabrication technology in which an uncured resin on a substrate is molded by using a mold and a resin pattern is formed on the substrate is gaining attention. This technology is called “imprint technology”, and a fine structure on the order of several nanometers can be formed on a substrate. One example of an imprint technology is a photo-curing method. In an imprint apparatus that uses this photo-curing method, first, an ultraviolet light-cured resin (imprint material, photo-cured resin) is applied to a shot, which is an imprint area on a substrate (wafer). Next, this resin (photo-cured resin) is molded by using a mold. In addition, by separating the resin after curing the resin by irradiating ultraviolet light, a resin pattern is formed on the substrate. In addition to this photo-curing method, there is also, for example, a heat-curing method in which, after molding a heat-cured resin on a substrate by using a mold, heat is applied, and the resin is separated after being cured to form a resin pattern.
In such an imprint apparatus, from the point of view of increasing the throughput, preferably, during the pressing of the mold and the resin on a substrate, the resin is quickly filled into a fine contoured pattern that is formed in the mold. At the same time, when using this imprint apparatus to manufacture, for example, a semiconductor device, the minimum line width of the circuit pattern is equal to or less than 100 nm, and in order to fill the resin reliably into the contoured pattern formed in a mold that satisfies this line width requirement, the resin must have a low viscosity. In this context, the imprint apparatus normally uses a step and repeat method, and repeats the pattern forming and the step movement for each shot on the substrate. At this time, because the resin has a low viscosity, applying in advance a resist (in this case, the resin) to all shots on the substrate as is done, for example, in an exposure apparatus, becomes difficult. Thus, in an imprint apparatus, generally the resin is applied (dropped) onto the shot using an inkjet method for each pattern to be formed on each shot, that is, each time the mold and resin are pressed together. However, with an inkjet method, when the resin that has been applied to the substrate and the mold are pressed together, bubbles easily become trapped in the uncured resin between the mold and the substrate. When the resin is cured with bubbles being retained as-is in this manner, there is a possibility that unfilled portions will occur in the resin pattern to be formed. Thus, as a countermeasure to suppress the occurrence of such unfilled portions, the specification of U.S. Pat. No. 7,360,851 discloses an imprint technology in which locations at which bubbles remain are specified by monitoring the spread of the resin during pressing with a camera, and the amount of drops of resin at this location is made large.
The imprint technology disclosed in U.S. Pat. No. 7,360,851 is one in which the application positions originally set are not changed, and the amount of drops of resin at locations at which bubbles are retained is made large. However, when the application position is not changed and the amount of resin is made large, there is a possibility that the evenness of the remaining film thickness after the imprint will be affected. That is, in the setting of the application positions, preferably the occurrence of unfilled portions should be suppressed beforehand.